Health

Why teenage boys do stupid things

An 18-year-old boy in Georgia drowns after he is tied to a shopping cart and pushed into a lake while horsing around with friends after his high school graduation. A young man, 19, causes a multi-car accident when he faints from holding his breath while driving through a tunnel in Portland, Ore.

Tragic stories of teens doing stupid things -- boys in particular -- constantly make the news. And there are biological reasons behind it: this type of risky, defiant and downright dangerous behavior has its roots in distinct differences in the developing brain of a young person.

"The brain of an adolescent is very different from the brain of an adult," Dr. Amir Levine, an adult, child and adolescent psychiatrist and neuroscientist at the division of child and adolescent psychiatry at Columbia University, told CBS News. "The brain goes through huge changes, initially it grows and then it shrinks. It basically undergoes what we call pruning, which means that the brain becomes more efficient and it does away with neurons that it doesn't need."

New data from the National Youth Risk Behavior Survey, released today by the Centers for Disease Control and Prevention, shows just how many teens engage in hazardous behavior.

The report finds that despite public health campaigns and a relative awareness, teens are still having unprotected sex; in 2013, the number of sexually-active teens who used condoms was 59 percent, down 4 points from a decade before. Teens also continue to text and drive even though more than 40 states have passed laws that make it illegal. Nationwide, 41 percent of students who have driven a vehicle during in the past 30 days reported they had texted or emailed while driving.

But the CDC report does offer a glimmer of hope because some risky behaviors have actually declined. The percentage of high school students nationwide who had been in a physical fight at least once during the past 12 months decreased from 42 percent in 1991 to 25 percent in 2013. Cigarette smoking is less common among young people as well. The report finds 15.7 percent of teenagers regularly smoked cigarettes in 2013.

Risky teen behavior can have deadly consequences. According the National Institutes of Health, death rates from accidents increase dramatically during early and late adolescence. Death by injury is as much as six times higher among teens age 15 to 19 than kids between age 10 and 14. Overall crime rates are highest among young males.

In the brazen teenage brain, the initial expansion in grey matter means neural pathways are more plentiful, which makes a young person more open to experiences and willing to try out and learn new things than adults generally are. But this can be a dangerous tendency -- even more so when teen brains join together in a pack.

Research has found that peer pressure activates certain brain signals that are linked to the powerful drug-like interplay of risk and reward. And a captive audience is the quickest way to bolster the brain's reward system.

That may be why teenage boys constantly egg each other on to fight, play harder, drink more and drive faster.

Laws in a number of states recognize the serious repercussions of this very real phenomenon. Forty-seven states now place restrictions on the number or age of passengers who can ride along with a teen driver, since teens having friends in the car has been found to be even more hazardous than alcohol intoxication when it comes to operating a motor vehicle.

"The daredevil brain, it goes into even hyper-mode when adolescents are in groups, and in general because testosterone causes more aggression," explained Levine. "Adolescents are very much conditioned to peer pressure. And we see again across species, even adolescent mice will drink a lot more alcohol when they're in a group of adolescent mice than adult mice when you give them the opportunity to drink alcohol."

And it doesn't help that sex is very suddenly -- and constantly -- on the male teen brain. Testosterone makes boys "push the envelope" even more.

Social and cultural roles further encourage risky behavior among young men. Michael Thompson, psychologist and author of three books about boys, including "It's a Boy!: Your Son's Development from Birth to 18," says risk-taking behavior is driven by the desire to fit into society's standards for masculinity.

"Boys believe there's a test to pass for manhood and this is different than a test for womanhood and femininity," he told CBS News. "You want to be brave and funny and tie yourself to a shopping cart."

Thankfully, however, the inherent differences of a teen brain can also facilitate positive and productive behavior, said Levine. These extra neural pathways fuel a young person's aspirations, interests and education and ultimately prepare them to thrive as an adult.